class_docstr: A class representing group homomorphisms. Instantiate using `homomorphism()`.
  
  References
  ==========
  
  .. [1] Holt, D., Eick, B. and O'Brien, E. (2005). Handbook of computational group theory.
code: def __init__(self, domain, codomain, images):
      self.domain = domain
      self.codomain = codomain
      self.images = images
      self._inverses = None
      self._kernel = None
      self._image = None
  
imports: import itertools
  from sympy.combinatorics.fp_groups import FpGroup, FpSubgroup, simplify_presentation
  from sympy.combinatorics.free_groups import FreeGroup
  from sympy.combinatorics.perm_groups import PermutationGroup
  from sympy.core.intfunc import igcd
  from sympy.ntheory.factor_ import totient
  from sympy.core.singleton import S
label_desc: Use image node_id 1 to create a new GroupHomomorphism object  with example: obj = GroupHomomorphism(domain, codomain, images)